Published: May 20, 2014 2:19 PM EDT

WASHINGTON (AP) - A top U.S. drug official says the United States is facing a "nationwide heroin crisis."
    
Assistant Secretary of State William Brownfield says heroin addicts and abusers have increased 75 percent in the last four years. He says the amount of pure heroin entering the U.S. has doubled.
    
Brownfield spoke Tuesday at a House Foreign Affairs Committee hearing on U.S.-Mexican relations. He heads the department's international narcotics and law enforcement unit.
    
Brownfield said the U.S. has gotten better at interrupting cocaine and methamphetamine flows from Latin America. But he said heroin is a different problem.
    
Law enforcement authorities across the U.S. are warning the drug is making a comeback. Once mainly a city phenomenon, it has spread to rural villages and middle-class suburbs.

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